JPH03216833A - Method of adhering optical disk - Google Patents

Abstract

PURPOSE:To reduce the time of adhering and to prevent cracks by coating a polymer resin protective film with UV-adhesion type adhesive by roll coating method, adhering the adhesive layers facing to each other by pressure and irradiation of UV ray. CONSTITUTION:After forming four-layer recording films 11a, 11b on plastic substrates 10a, 10b, respectively, having track guide grooves on the one side of the substrate, UV-curing resin films (protective films) 12a, 12b are formed to constitute single plate disks D1, D2. Then UV-adhesion type adhesive 13 is applied on the protective film side of the disks D1, D2 by roll coating method. The disk is irradiated with UV ray, the coated surface are made to face each other and pressed to adhere. By this method, time required for adhesion can be decreased and the disk has excellent mechanical property without cracks.

Description

Detailed Description of the Invention (a) Industrial Application Field The present invention relates to a method of adhering an optical disk, in which two magneto-optical recording disks are bonded with their recording film sides facing each other, and in particular, relates to a method for bonding an optical disk, in which the recording film sides of two magneto-optical recording disks face each other and are bonded. The present invention relates to a method of adhering a double-sided optical disc used for the enhancement layer and the protective layer of the medium layer.

(Example) The conventional technology for magneto-optical recording disks is AIN. A dielectric thin film such as SiN is used for the enhancement layer and the protective layer of the recording medium layer. If plastic is used for the substrate and heat treatment is included in the process of bonding the two disks together, cracks will occur in the recording film due to the difference in thermal expansion coefficient between the dielectric thin film and the substrate during heating. , may cause playback signal defects (increase in hit error rate, etc.).

In addition, in the bonding process, it is necessary to correct mechanical properties such as warping of the disks that occurred in the previous process, so in order to maintain the flatness of the substrate, it is necessary to bond the two disks together under pressure. is considered desirable.

For this reason, there is a need for an adhesive method that does not cause deterioration of recorded and reproduced signals, specifically a pressure adhesive method that provides excellent mechanical properties and does not involve a heating process. .

Typical adhesives conventionally used for laminating optical disks are: 1) hot melt type, 2) ultraviolet (UV) curing type, and 3) epoxy resin two-component mixture type.

(c) Problems to be Solved by the Invention Among these, hot-melt adhesives are the most widely used adhesives for adhering laser discs.

Hot-melt type adhesives have high mechanical properties and mass productivity because they can be applied using a roll coater and bonded under pressure. This is not desirable as it may cause a crack.

Ultraviolet curable adhesives can be cured at room temperature by imparting anaerobic properties, but when pressure bonding is performed after application, the adhesive oozes into the center hole and outer edge of the disk. Since the eccentricity of the disk is determined by the accuracy of the center hole, there is a problem in that such an adhesive that wraps around the center hole increases the eccentricity of the disk and significantly deteriorates its mechanical properties.

In addition, the two-component epoxy resin adhesive can be cured at room temperature and has the most stable physical properties after curing, but the usable time (pot life) after mixing the base resin and curing agent is 2. It is short, less than an hour, and the workability is poor. Additionally, it has the same drawbacks as the UV-curable type when it comes to coating.

The present invention was made in order to solve the above-mentioned drawbacks of the prior art. Specifically, the present invention enables coating by a roll coater and pressure bonding at room temperature, and enables mass production of magneto-optical disks using a process similar to that used for laser disks. The present invention provides a method for adhering optical discs that enables processing.

(2) Means and Effects for Solving the Problems In order to achieve the above object, the optical disk adhesion method adopted by the present invention consists of a transparent synthetic resin substrate and a dielectric layer formed on the track guide groove on one side of the substrate. a step of applying an ultraviolet adhesive adhesive by a roll coating method onto the surface of the polymer resin protective film of a disk comprising a recording film containing a recording film and a polymer resin protective film provided on the recording film, the applied adhesive; A method for adhering double-sided optical discs consists of a step of irradiating the layer with ultraviolet rays and a step of adhering the adhesive layers of two discs produced by the above method to each other under pressure. The ultraviolet ray adhesive is an adhesive that develops tackiness by irradiation with ultraviolet rays, and specifically, an acrylic adhesive can be used.

(e) Examples Hereinafter, the present invention will be explained in detail based on examples with reference to the drawings.

FIG. 1 shows a sectional view of a double-sided magneto-optical recording disk. 130mmφPMMA with track guide groove on one side
(Polymethyl methacrylate) A I N. Tb
Four-layer recording film 11a of FeCo, AI N, AI
, 151m by spin coating.
Ultraviolet curing resin film (protection 11i) 12a. 12b (manufactured by Dainippon Ink Co., Ltd., EX-1) to prepare veneer disks Di and D2. This single plate disc DI,D
Ultraviolet adhesive adhesive 13 (manufactured by Cemedine Co., Ltd. CT-1 1 0K viscosity 10000 cps/20
℃) to a thickness of approximately 30 pm, and then irradiated with ultraviolet rays (high pressure mercury lamp 365 nm approximately 500 nm).
mJ/cs+'') L, the coated surfaces were placed facing each other and bonded under pressure. The disk thus obtained is referred to as disk 1.

For comparison, an ultraviolet curing adhesive (BU-130U manufactured by Toagosei Kagaku Co., Ltd.) with anaerobic properties that can be cured at room temperature was used.
A bonded disk was prepared with a viscosity of 1000 cps/20°C. Adhesion is done at one radius of 4 of the above single plate disc.
Apply approximately 3 cm of UV-curable adhesive in concentric circles at a distance of 5 mm.
After applying c, the other disk was placed on top of the other disk, and the adhesive was spread over the entire surface of the disk by its own weight, and both surfaces were irradiated with ultraviolet light at an amount of 600 mJ/cn+1. The disk obtained by the above method is called disk 2. At that time, when pressure is applied to correct warpage, the center hole and surface of the disk are found to wrap around, and even when the amount of coating is adjusted and pressure is applied, the adhesive layer may curl due to individual differences in the warp of the veneer disk. There were cases where a thin part was formed and the product partially peeled off after curing.

FIG.
A schematic diagram of a track error signal in 0-orpm sujiru jump mode is shown. Still jump signal amplitude (A
) and the error signal amplitude (B) during trunk tracking (B/
A) is a disk! The deterioration was about 0.09 for disk 2, while it was about 0.17 for disk 2, and it can be seen that the difference in mechanical properties such as upward runout occurs due to the difference in the bonding process.

In addition, with adhesives that are fluid during lamination, such as UV-curable adhesives, it is difficult to avoid adhesion of the adhesive to the readout surface of the disc, including when handling during work, and trop-outs occur due to the above-mentioned adhesion. .

(F) Effects of the Invention As described above, by using the optical disc adhesion method of the present invention, it is possible to obtain a double-sided optical disc with excellent mechanical properties and no deterioration of properties due to cracks occurring during the adhesion process. . Furthermore, since the same roll coater coating/pressure adhesion as used for laser discs can be used for adhesion, the time required for adhesion can be shortened, and optical discs with excellent mechanical properties can be manufactured at low cost.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view of a double-sided optical disc according to an embodiment of the present invention, and FIG. 21 is a schematic diagram for explaining a track error signal in the embodiment. 10a 10b...Plastic board, 11
'a. Ilb...Recording film including dielectric layer, 12
a. 12b...Polymer resin protective film, l3...Adhesive layer.

Claims (1)

[Claims] 1. On the surface of a polymer resin protective film in a disk consisting of a transparent synthetic resin substrate, a recording film including a dielectric layer formed on a track guide groove on one side of the substrate, and a polymer resin protective film provided on the recording film. A step of applying an ultraviolet adhesive adhesive by a roll coating method, a step of irradiating the applied adhesive layer with ultraviolet rays, and a step of pressing and bonding the adhesive layers of two disks produced by the above method facing each other. A method for adhering double-sided optical discs, which consists of the following steps: